Internet Engineering Task Force (IETF) F. Le Faucheur, Ed.
Request for Comments: 6398 Cisco
BCP: 168 October 2011
Updates: 2113, 2711
Category: Best Current Practice
ISSN: 2070-1721
IP Router Alert Considerations and Usage
Abstract
The IP Router Alert Option is an IP option that alerts transit
routers to more closely examine the contents of an IP packet. The
Resource reSerVation Protocol (RSVP), Pragmatic General Multicast
(PGM), the Internet Group Management Protocol (IGMP), Multicast
Listener Discovery (MLD), Multicast Router Discovery (MRD), and
General Internet Signaling Transport (GIST) are some of the protocols
that make use of the IP Router Alert Option. This document discusses
security aspects and usage guidelines around the use of the current
IP Router Alert Option, thereby updating RFC 2113 and RFC 2711.
Specifically, it provides recommendations against using the Router
Alert in the end-to-end open Internet and identifies controlled
environments where protocols depending on Router Alert can be used
safely. It also provides recommendations about protection approaches
for service providers. Finally, it provides brief guidelines for
Router Alert implementation on routers.
Status of This Memo
This memo documents an Internet Best Current Practice.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
BCPs is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6398.
Le Faucheur Best Current Practice [Page 1]RFC 6398 Router Alert Considerations October 2011Copyright Notice
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Table of Contents
1. Introduction ....................................................3
2. Terminology .....................................................4
2.1. Conventions Used in This Document ..........................4
3. Security Concerns of Router Alert ...............................5
4. Guidelines for Use of Router Alert ..............................7
4.1. Use of Router Alert End to End in the Internet
(Router Alert in Peer Model) ...............................7
4.2. Use of Router Alert in Controlled Environments .............9
4.2.1. Use of Router Alert within an Administrative
Domain ..............................................9
4.2.2. Use of Router Alert in Overlay Model ...............11
4.3. Router Alert Protection Approaches for Service Providers ..13
5. Guidelines for Router Alert Implementation .....................15
6. Security Considerations ........................................16
7. Contributors ...................................................16
8. Acknowledgments ................................................16
9. References .....................................................17
9.1. Normative References ......................................17
9.2. Informative References ....................................17
Le Faucheur Best Current Practice [Page 2]RFC 6398 Router Alert Considerations October 20111. Introduction
[RFC2113] and [RFC2711] define the IPv4 and IPv6 Router Alert Options
(RAOs), respectively. In this document, we collectively refer to
those options as the IP Router Alert. The IP Router Alert Option is
an IP option that alerts transit routers to more closely examine the
contents of an IP packet.
Some of the protocols that make use of the IP Router Alert are the
Resource reSerVation Protocol (RSVP) ([RFC2205], [RFC3175],
[RFC3209]), Pragmatic General Multicast (PGM) ([RFC3208]), the
Internet Group Management Protocol (IGMP) ([RFC3376]), Multicast
Listener Discovery (MLD) ([RFC2710], [RFC3810]), Multicast Router